1. Field of the Invention
The present invention relates to a scroll compressor, and more particularly, to a scroll compressor having a groove for receiving a seal member of a scroll shape.
2. Description of Related Art
Prior art scroll compressors include a stationary scroll member having a scroll wall and a movable scroll member having a scroll wall, which is arranged in a side-by-side contact relationship with respect to the scroll wall of the stationary scroll member, thus defining closed chambers between the stationary and movable scroll members. A mechanism is provided for preventing self rotation of the movable scroll member, while allowing orbital movement of the movable scroll member about an axis of a drive shaft, so that the closed chambers move radially inwardly while their volumes are reducing. Furthermore, the end of the scroll wall of each of the stationary and movable scroll members has a thickness larger than the remaining part of the scroll wall, and is formed with a recess for receiving a scroll shaped seal member, which is in sealing contact with a facing surface of the base plate of the opposite scroll member. During the operation of the scroll compressor, the closed chambers are moved radially toward inner ends of the scroll walls of the stationary and movable scroll members, so that compressed refrigerant gas is discharged to an outlet port.
High pressure of the refrigerant gas in the chambers during the compression subjects the inner ends of the scroll walls of the stationary and movable scroll members to higher temperature and a higher pressure of the refrigerant gas in comparison with the other parts of the scroll walls. The scroll walls are made integral with respect to the base plates in order to increase the strength and the rigidity of the scroll walls. However, the scroll walls are cut out at the inner ends of the scroll walls, causing the strength as well as the rigidity to be reduced. In other words, the scroll walls are apt to be damaged at the inner ends when subjected to the high temperature and the high pressure of the refrigerant gas.
Japanese Examined Patent Publication No. 1-30637 discloses a scroll compressor, wherein an inner end of the scroll wall has an increased width, thereby increasing its strength and rigidity. The width of the groove for receiving the seal member on the end surface of the scroll wall is also increased at the location corresponding to the inner end of the scroll wall.
The scroll member is made from a molding, such as a die-casting. The groove is machined using a machine tool, in the molded surface of the scroll member. Specifically, an end mill with a machine tool of a diameter corresponding to the width of the groove is introduced onto the molded surface. At the inner end of the scroll wall, the width is increased to a value more than twice the width of the wall at the outer end, so that a single pass of the machine tool is insufficient to obtain a desired width of the groove, which is more than twice the width of the groove at the outer end. Thus, a reciprocal movement of the machine tool is necessary at the inner end of the scroll wall to machine the grooves. As a result, the labor required to complete the machining is increased.